Sulfur boron antiwear agents for lubricating compositions

ABSTRACT

Sulfur-containing boroester compounds useful as antiwear additives for oleaginous compositions including alicyclic borate thioesters having the general formula (I): ##STR1## wherein R 1  is a hydrocarbyl radical having 4 to 12 carbon atoms, R 2  and R 3  are independently selected from --(OR 4 ) n  SR 1  and --(OR 4 ) n  SR 1  OH; R 4  is a hydrocarbyl radical having 1 to 6 carbon atoms; n is an integer of from 1 to 4; and l and m are independently 0, 1 or 2; thioalkyl-substituted cyclic meta borate esters having the general formula (II): ##STR2## wherein n, R 1  and R 4  are defined as in formula (I); and mixtures of the alicyclic compounds of formula (I) and the cyclic compounds of formula (II).

The invention relates generally to compounds useful as antiwearadditives for oleaginous compositions. In particular, the presentinvention relates to alicyclic borate thioester and cyclic meta boratethioalkylester compounds suitable for use as antiwear additives forlubricating and power transmitting oils or fluids.

BACKGROUND OF THE INVENTION

Boron-containing compounds, and particularly borate esters are known toact as antiwear agents when added to lubricating oils. EP-A-0216909discloses antiwear agents that are esters of metaboric acid, and havethe following formula: ##STR3## wherein each R is independently hydrogenor a hydrocarbyl group containing from 1 to 18 carbon atoms and each R'is independently an alkylene group containing from 2 to 4 carbon atoms.

It is further well known that sulfur-containing compounds act asanti-oxidants in lubricating compositions and can further enhance theeffect of boron-based antiwear agents. The above described EuropeanPatent Specification discloses the use of the defined metaboric acidester in combination with an oil soluble sulfurized organic compound inrelative amounts sufficient to provide a weight ratio of sulfur to boronof from 0.5:1 to 20:1.

Antiwear agents providing both boron and sulfur are disclosed, forexample, U.S. Pat. No. 3,303,130 describes an organo thioalkyl borateantiwear agent of the general formula: ##STR4## wherein R is selectedfrom the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl andcycloalkyl radicals containing 1 to 16 carbon atoms and n is an integerof 2 to 16, inclusive. These compounds are formed by reacting athioalcohol with boric acid in a molar ratio of at least 3:1, andprovide an antiwear additive having a weight ratio of sulfur to boron of3.33:1. Similar compounds formed by reacting an alcohol, ahydroxysulfide and a boron compound, and the use thereof as a frictionreducer in lubricating oil compositions are disclosed in U.S. Pat. No.4,492,640.

Because of increased demand for lubricating oil additives and fiercecompetition between manufacturers, there has been a continued need forimproved antiwear additives. The present inventors have developed animproved antiwear additive for lubricating oils which comprises a singlecompound that provides a relatively high weight ratio of boron tosulfur, while simultaneously providing antioxidant and friction modifierproperties.

Other objects, advantages and features of the present invention will beunderstood by reference to the following specification.

SUMMARY OF THE INVENTION

The present invention, in brief summary, is directed to alicyclicthioalkyl borate esters of the formula (I): ##STR5## wherein R₁ is ahydrocarbyl radical having between about 4 to 12 carbon atoms, R₂ and R₃are independently selected from --(OR₄)_(n) SR₁ and --(OR₄)_(n) SR₁ OH;R₄ is a hydrocarbyl radical having between about 1 to 6 carbon atoms; nis an integer of from between about 1 to 4; and l and m areindependently 0, 1 or 2; (b) thioalkyl-substituted cyclic meta borateesters of formula (II): ##STR6## wherein n, R₁ and R₄ are defined as informula (I); and (c) mixtures of the alicyclic compounds of formula (I)and the cyclic compounds of formula (II).

The present invention is further directed to lubricating oil and powertransmitting oil compositions containing at least one antiwear agentselected from the group consisting of: alicyclic compounds of formula(I), cyclic compounds of formula (II), and mixtures thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The alicyclic borate thioester and cyclic meta borate thioester antiwearadditives of the present invention are the product of a condensationreaction of an alkoxyalkyl sulfide and boric acid in a molar ratio of atleast about 1:1. Suitable alkoxyalkyl sulfides are compounds of formula(III):

    R.sub.1 SR.sub.4 OH                                        (III)

wherein R₁ is a hydrocarbyl radical having between about 4 to 12 carbonatoms and R₄ is a hydrocarbyl radical having between about 1 to 6 carbonatoms. Preferable compounds of formula III include hydroxyethyldodecylsulfide, 1-hydroxy-2-methyl-3-thio-decane and hydroxyethyloctyl sulfide(HEOS). The alkoxyalkyl sulfide can comprise a single compound or amixture thereof.

When reacted with boric acid, the alkoxyalkyl sulfide will form areaction product that can include both the alicyclic compound of formulaI and the cyclic compound of formula II. The reaction strongly favorsformation of the cyclic meta borate thioester and the reaction productmay, in fact, contain only insignificant amounts, or essentially no,alicyclic borate thioester. The boric acid and hydroxalkyl sulfide arereacted in a molar ratio of about 1:1 or can be reacted in the presenceof a slight molar excess of alkoxyalkyl sulfide (no greater than about2:1). The reaction is conducted at a temperature within a range of frombetween about 0° to 150° C., preferably from between about 60° to 120°C., and at a pressure within a range from between about -100 to 0 kPa,preferably from between about -70 to -30 kPa.

The boric acid and hydroxalkyl sulfide may be reacted either neat or inan inert or non-participating polar solvent. Using hydroxyethyloctylsulfide (HEOS) and boric acid reactants as examples, the reaction isbelieved to proceed as follows: ##STR7##

Lubricating oils and power transmitting oils to which the antiwearadditives of the invention can be advantageously added are derived fromnatural oils, synthetic oils or mixtures of natural oils and syntheticoils. Suitable oils include base stocks obtained by isomerization ofsynthetic wax and slack wax, as well as base stocks produced byhydrocracking the aromatic and polar components of the crude.

Synthetic oils include hydrocarbon oils and halo-substituted hydrocarbonoils such as oligomerized, polymerized and interpolymerized olefins(e.g., polybutylenes, polypropylenes, propylene, isobutylene copolymers,chlorinated polyactenes, poly(1-hexenes), poly(1-octenes),poly(1-decenes), and mixtures thereof); alkylbenzenes (e.g.,dodecylbenzenes, tetradecylbenzenes, dinonyl-benzenes,di(2-ethylhexyl)benzene); polyphenyls (e.g., biphenyls, terphenyls,alkylated polyphenyls); and alkylated diphenyl ethers, alkylateddiphenyl sulfides, as well as derivatives, analogs and homologs thereof.

Synthetic oils also include alkylene oxide polymers, interpolymers,copolymers and derivatives thereof where the terminal hydroxyl groupshave been modified by esterification, etherification, etc. This class ofsynthetic oils can be exemplified by polyoxyalkylene polymers preparedby polymerization of ethylene oxide or propylene oxide; as well as thealkyl or aryl ethers of these polyoxy-alkylene polymers (e.g.,methyl-polyisopropylene glycol ether having a number average molecularweight of 1000 and diphenyl ether of polypropylene glycol having anumber average molecular weight of about 1000 to about 1500); and mono-and poly-carboxylic esters thereof (e.g., acetic acid esters, mixed C₃to C₈ fatty acid esters and C₁₂ oxo diester of tetraethylene glycol).

Another suitable class of synthetic lubricating oils comprises theesters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkylsuccinic acids and alkenyl succinic acids, maleic acid, azelaic acid,subric acid, sebasic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkylmalonic acids and alkenyl malonic acids) withan alcohol (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoethers andpropylene glycol). Specific examples of these esters include dibutyladipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctyl azelate, diisodecyl azelate, dioctyl isothalate,didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester oflinoleic acid dimer, and the complex ester formed by reacting one moleof sebasic acid with two moles of tetraethylene glycol and two moles of2-ethyl-hexanoic acid.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol ethers such as neopentylglycol, trimethylolpropane pentaerythritol, dipentaerythritol,tripentaerythritol, and the like.

Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy- orpolyaryloxy-siloxane oils and silicate oils) comprise another usefulclass of synthetic oils. These oils include tetra-ethyl silicate,tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate,tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert- butylphenyl)silicate, hexa-(4-methyl-2-pentoxy)-disiloxane, poly(methyl) siloxanesand poly(methylphenyl) siloxanes. Other synthetic lubricating oilsinclude liquid esters of phosphorous-containing acids (e.g., tricresylphosphate, trioctyl phosphate, and diethyl ester of decylphosphonicacid), polymeric tetra- hydrofurans, poly-α-olefins, and the like.

Natural oils include animal oils, vegetable oils (e.g., castor oil andlard oil), petroleum oils, mineral oils, and oils derived from coal orshale. Mineral oils to which the antiwear additives of the invention canbe added include all common mineral oil base stocks. This includes oilsthat are napthenic or paraffinic in chemical structure. The oils may berefined by conventional methodology using acid, alkali, and clay orother agents such as aluminum chloride, or they may be extracted oilsproduced, for example, by solvent extraction with solvents such asphenol, sulfur dioxide, furfural or dichlordiethyl ether, etc. They mayalso be hydrotreated or hydrorefined, dewaxed by chilling or bycatalytic processing, or hydrocracked. The mineral oil may also beproduced from natural crude sources or be composed of isomerized waxmaterials or residues of other refined processes.

The lubricating or power transmitting oils may be derived from unrefinedoils, highly refined oils, re-refined oils or mixtures thereof.Unrefined oils are obtained directly from natural sources or syntheticsources (e.g., shale or tar sands bitumen) without further purificationor treatment. Examples of unrefined oils include a shale oil obtaineddirectly from a retorting operation, a petroleum oil obtained directlyfrom distillation, or an ester oil obtained directly from anesterification process, each of which is used without further treatment.Refined oils are similar to unrefined oils except that the refined oilshave been treated in one or more purification steps to improve one ormore properties. Suitable purification techniques include distillation,hydrotreating, dewaxing, solvent extraction, acid or base extraction,filtration and percolation, all of which are known to those of ordinaryskill in the art. Re-refined oils are obtained by treating used oils inprocesses similar to those used to obtain the refined oils. Thesere-refined oils are also known as reclaimed or reprocessed oils and areoften additionally processed by techniques for removal of spentadditives and oil breakdown products.

The compounds of the invention can be incorporated into lubricating oilsand power transmitting oils as an antiwear additive in an amount frombetween about 0.001 to 5 wt. %, preferably from between about 0.001 to1.5 wt. %, most preferably from between about 0.2 to 1.0 wt. %. Theoleaginous materials may be formulated to contain other additives suchas viscosity modifiers, auxiliary antioxidants, friction modifiers,dispersants, antifoaming agents, auxiliary antiwear agents, pour pointdepressants, detergents, rust inhibitors and the like.

Compositions containing the above additives are typically blended intobase oils in amounts sufficient to provide their normal attendantfunction. Representative examples of amounts in which these additivesare conventionally to lubricating oils are as follows:

    ______________________________________    Additive       Wt. % (broad)*                               Wt. % (preferred)*    ______________________________________    Viscosity Modifier                   .01-12      .01-4    Corrosion Inhibitor                   .01-5       .01-1.5    Oxidation Inhibitor                   .01-5       .01-1.5    Dispersant     .1-20       .1-8    Pour Point Depressant                   .01-5       .01-1.5    Anti-Foaming Agents                   .001-3      .001-0.15    Anti-Wear Agents                   .001-5      .001-1.5    Friction Modifiers                   .01-5       .01-3    Detergents/Rust Inhibitors                   .01-10      .01-3    Base Oil       Balance     Balance    ______________________________________     *active ingredient

The additives can be incorporated into the lubricating oil in anyconvenient manner. Thus, they can be added directly to the oil bydispersing or dissolving same in the oil. Such blending can be performedat room temperature or at elevated temperatures. Alternatively, theadditives may be first formed into concentrates, which are subsequentlyblended with the oil. The final formulations may typically contain frombetween about 2 wt. % to 20 wt. % of additives.

Suitable dispersants include hydrocarbyl succinimides, hydrocarbylsuccinamides, mixed ester/amides of hydrocarbyl substituted succinicacid, hydroxyesters of hydrocarbyl-substituted succinic acid, amides ofaromatic acids and Mannich condensation products ofhydrocarbyl-substituted phenols, formaldehyde and polyamines. Mixturesof such dispersants can also be employed. The dispersants may optionallybe post treated with conventional reagents known in the art (see, e.g.,U.S. Pat. Nos. 3,254,025; 3,505,677; and 4,857,214).

The preferred dispersant for use in combination with the sulfur boronantiwear additives of the present invention are alkenyl succinimides.These acyclic hydrocarbyl substituted succinimides are formed withvarious amines, polyamines and amine derivatives, and are well known tothose of ordinary skill in the art. An example of a particularlysuitable dispersant is the polyisobutenyl succinimide reaction productof polyisobutylene succinic anhydride, wherein the polyisobutene moietypreferably has a number average molecular weight in the range frombetween about 500 to 5000, preferably from between about 800 to 2500 andan alkylene polyamine such as triethylene tetramine or tetraethylenepentamine or mixtures of polyamines containing 3 to 12 nitrogen atomsper molecule, known in the art as PAM. The use of alkenyl succinimidesthat have been treated with an inorganic acid of phosphorus (or ananhydride thereof) and a boronating agent are also suitable for use incombination with the compounds of the invention and are more compatiblewith elastomeric seals made from such substances as fluoroelastomers andsilicon-containing elastomers.

Suitable antioxidants for use in combination with the additives of thepresent invention include amine-type and phenolic antioxidants. Examplesof amine-type antioxidants include phenyl alpha napthylamine, phenylbeta naphthalyamine and bis- alkylated diphenyl amines (e.g.,p,p'-bis(alkylphenyl)-amines wherein the alkyl groups each contain from8 to 12 carbon atoms). Phenolic antioxidants include sterically hinderedphenols (e.g., 2,6-di-tert-butylphenol,4-methyl-2,6-di-tert-butylphenol) and bis-phenols (e.g.,4,4"-methylenebis(2,6-di-tert-butylphenol). Phosphorous compounds, suchas ZDDP, or phosphites are also commonly added to automatic transmissionfluids (ATF) and passenger car motor oils (PCMO) as antioxidants. Inaddition to providing antiwear properties, the compounds of the presentinvention provide antioxidant credits to lubricating compositions,allowing for the formulation of lubricating compositions with a reducedamount, or no amount, of dedicated antioxidant additive.

Suitable friction modifiers are molecules having a polar head group andan oleophilic tail group. The polar head groups cause the molecule to beadsorbed onto the friction surface. These groups can be, but are notlimited to, amines, mono and diethoxylated amines, carboxylic acids,amides, imides, alcohols, phenols, thiols, sulfonic acids, phosphites,phosphates, esters and combinations thereof. The oleophilic groups aretypically alkyl groups, normally linear alkyl groups. These alkyl groupsrange in carbon number from between about C₈ to C₃₀, preferably from C₁₂to C₂₀. They may be saturated or unsaturated, and may contain heteroatoms such as nitrogen or sulfur providing that the hetero atoms do notadversely affect the ability of the molecule to function as a frictionmodifier.

Examples of friction modifiers suitable for use with the antiwearadditives of the invention include oleamide, tallow amine, diethoxylatedtallow amine, N,N-bis(2-hydroxyethyl)-octadecyl amine,N,N-bis(2-hydroxyethyl)-stearyloxypropylamine, oleic acid,N,N-hydroxyethyl,N-(N',N'-bis(2-hydroxyethyl)ethylamine)-stearylamineand the diamide produced from isostearic acid and tetraethylenepentamine.

Suitable compounds for use as viscosity modifiers are generally highmolecular weight hydrocarbon polymers, including polyesters. Oil solubleviscosity modifying polymers generally have weight average molecularweights from about 10,000 to 1,000,000, preferably from about 20,000 to500,000, as determined by gel permeation chromatography or lightscattering methods.

Representative examples of suitable viscosity modifiers arepolyisobutylene, copolymers of ethylene and propylene and higheralpha-olefins, polymethacrylates, polyalkylmethacrylates, methacrylatecopolymers, copolymers of unsaturated dicarboxylic acid and vinylcompound, inter polymers of styrene and acrylic esters, and partiallyhydrogenated copolymers of styrene/isoprene, styrene/butadiene andisoprene/butadiene, as well as partially hydrogenated homopolymers ofbutadiene and isoprene and isoprene/divinylbenzene.

Lubricating oils and power transmission oils incorporating the antiwearadditives of the invention may also contain rust inhibitors such asnonionic polyoxyalkylene polyols and esters thereof, polyoxyalkylenephenols and anionic alkyl sulfonic acids, as well as corrosioninhibitors, such as thiadiazole polysulfides containing from betweenabout 5 to 50 carbon atoms, their derivatives and polymers thereof;derivatives of 1,3,4-thiadiazoles; and thio and polythio sulfenamides ofthiadiazoles. Such oils may also contain an antifoamant, includingpolyacrylate-type antifoamants, polysiloxane-type antifoamants andfluorosilicone-type antifoamants, and detergents, such as overbased andneutral calcium sulfonate, calcium phenate, magnesium sulfonate andmagnesium phenate.

EXAMPLES Synthesis Example 1

In a 5 liter, three neck flask, 2280 grams of hydroxyethyloctyl sulfide(12 mol) and 744 grams of boric acid powder (12 mol) are combined. Theflask is equipped with a stirrer, a thermometer and a condenser that isconnected to vacuum. The flask is heated to 110° C., and pressure withinthe flask is reduced to -70 kPa. After a few minutes water begins toevolve. The temperature in the flask is allowed to fall to 100° C. atwhich point heating is terminated and the exothermic reaction proceedsunassisted until 2 molar equivalents of water evolve and are collected.Heat is then applied until one additional molar equivalent of waterevolves and is collected.

The product was characterized by a combination of analytical techniques.HPLC separation analysis shows that one primary species was formed. ¹³ CNMR Spectroscopy indicated that the material had a characteristic sharpsingle resonance associated with a borated alkoxy methylene carbon at62.8(1 C) ppm relative to TMS. ¹¹ B NMR Spectroscopy shows only oneboro-oxygen ester signal at -3 ppm relative to H₃ BO₃. The simplicity ofthe carbon and boron NMR spectral result are indicative of a highlysymmetric meta-boroester structure. Characteristic carbon signalsassociated with the incorporation of hydroxyethyloctyl sulfide werefound at 33(1C), 31.8(1C), 31.2(1C), 29.6(1C), 28.8(1C), 28.6(1C),22.4(1C) and 13.6(1C).

Example 2

To demonstrate the ability of the compounds of the present invention toprovide antiwear and antioxidant activity in lubricating oils, AdditivePackages (Adpacks) A through G were formulated as shown below and addedto a viscosity modified base oil at a 7 mass % treat rate to formformulated oils. The formulated oils were then subjected to LMOT testing(described below) to determine antioxidancy improvements, and FZGtesting (Four Square Gear Test, ASTM-D-5 182) to determine antiwearactivity.

The Laboratory Multiple Oxidation Test (LMOT) is used to measure theability of lubricant compositions to resist heat and air oxidation. Inthe LMOT, 50 cc of a test lubricant, 2.2 g of iron filings, and 0.5 g ofa 1% copper solution (Nuodex® Copper 82 copper naphthenate in mineralspirits made into a 1% solution by dissolution of Nuodex 8% copper in100NLP oil (Exxon Chemical)). At a temperature of 150° C. ±2° C., air ispassed through the sample (25 cc+2 cc/min.). One drop per day of thesample lubricant is placed on a blotter until sludge appears. Theresults of the LMOT are presented in terms of days until sludge isobserved (days to failure).

Adpack A

3.5% borated PIBSA/PAM 950 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.45% HEOS-meta borate ester of Example 1;0.15% friction modifiers; 0.001% fluorinated silicone antifoamant; and2.439% base stock oil (all pecentages given as mass %).

Adpack B

3.5% borated PIBSA/PAM 950 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.45% HEOS-meta borate ester of Example 1;0.50% tolyl triazole (corrosion inhibitor) 0.15% friction modifiers;0.001% fluorinated silicone antifoamant; and 1.939% base stock oil (allpecentages given as mass %).

Adpack C

3.5% borated PIBSA/PAM 2200 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.45% HEOS-meta borate ester of Example 1;0.15% friction modifiers; 0.001% fluorinated silicone antifoamant; and2.439% base stock oil (all pecentages given as mass %).

Adpack D

3.5% borated PIBSA/PAM 2200 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.45% HEOS-meta borate ester of Example 1;0.50% tolyl triazole (corrosion inhibitor) 0.15% friction modifiers;0.001% fluorinated silicone antifoamant; and 1.939% base stock oil (allpecentages given as mass %).

Adpack E

3.5% borated PIBSA/PAM 950 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.15% friction modifiers; 0.001%fluorinated silicone antifoamant; and 2.899% base stock oil (allpecentages given as mass %).

Adpack F

3.5% borated PIBSA/PAM 950 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.92% HEOS-meta borate ester of Example 1;0.15% friction modifiers; 0.001% fluorinated silicone antifoamant; and2.899% base stock oil (all pecentages given as mass %).

Adpack G

3.5% borated PIBSA/PAM 2200 Mw isobutylene (dispersant); 0.45%diphenylamine (antioxidant); 0.92% HEOS-meta borate ester of Example 1;0.50% tolyl triazole (corrosion inhibitor); 0.15% friction modifiers;0.001% fluorinated silicone antifoamant; and 1.479% base stock oil (allpecentages given as mass %).

                  TABLE 1    ______________________________________             A    B      C      D    E    F    G    ______________________________________    Viscosity  8.2    8.2    8.8  8.9  8.0  8.6  10.0    at 100° C. (cS)    LMOT       8.5    9      11   10   7    11   11    at 320° F.    (days to failure)    FZG        --     --     --   10   8    11   12    (failure stage)    ______________________________________

As shown by the data of Table 1, the addition of adpack D, containing0.46 mass % HEOS meta borate ester, to the base stock oil, improved theFZG by two load stages compared to an oil formulated without the borateester (Adpack E). The use of additional HEOS meta borate ester (AdpacksF and G) led to further improvement in antiwear properties. The resultsof the LMOT testing display the ability of the HEOS meta borate ester tosimultaneously function as an antioxidant. Specifically, the dataregarding Adpacks A through D, containing 0.46 HEOS meta borate ester,demonstrate an increased LMOT of 1.5 to 3 days compared to the oilformulated without the additive of the invention (Adpack E) The additionof Adpack F or G, which contained 0.92 mass % of the HEOS meta borateester provided a four day increase in the LMOT result compared to thecomposition formulated with Adpack E.

Example 3

To demonstrate the results achieved when the additives of the inventionare co-formulated with commonly used phosphorous-based additives, threeoil compositions were formulated to contain 0.31 mass % HEOS meta borateester and either 0.30 mass % triphenylphosphate (TPP) (Adpack H); 0.16mass % of mixed phosphites (Adpack I); or 0.19 mass % dibutyl phosphite(DBP) (Adpack J). The three formulated oils were subjected to FZG andLMOT testing. The results are shown below:

                  TABLE 2    ______________________________________                 H       I         J    ______________________________________    Viscosity      8.03      7.99      7.99    at 100° C. (cS)    LMOT           10.5      9         10.5    at 320° F.    (days to failure)    FZG            9         10        12    (failure stage)    ______________________________________

The data of Table 2 demonstrates that an adpack containing HEOS metaborate ester (0.31 mass %), co-formulated with phosphorous-basedfriction modifiers, simultaneously provide antiwear and antioxidantproperties in formulated oils.

Example 3

The antiwear properties of HEOS meta borate (0.31 wt. %)-dispersantcombinations (PIBSA PAM (950 Mw polyisobutylene)) (3.5 wt. %), in whichthe HEOS-meta borate ester in an automatic transmission fluid (K) werecompared to a fully formulated reference ATF (L) (containing nophosphorous-based, or other antiwear additives) in the industry standardFord MERCON Vickers Pump Test (Ford Motor Company, MERCON AutomaticTransmission Fluid Specification for Service, Mar. 5, 1987). The strongantiwear performance of the borate ester-dispersant combination, shownbelow in Table 3, was surprising given that the ATF contained no otherantiwear additives. The data of Table 4 compares the measured VickersPump wear for the additized oil to the industry standards.

                  TABLE 3    ______________________________________    Additive Combination                   FZG Failing Load Stage    ______________________________________    K              13    L               8    ______________________________________

                  TABLE 4    ______________________________________    ATF Fluid Wear Result                   GM Dextron III* Pass/Fail Limit    ______________________________________    12.mg Total Wear                   15 mg maximum Total Wear    ______________________________________     *Hydra-matic Division, General Motors Corp.

Example 4

To demonstrate the antiwear performance of the HEOS meta borate esterand dispersant combination in passenger car motor oils (PCMO), a PCMOcontaining 3.5 wt. % of a standard PIBSA-PAM clispersant (M) wascompared to a PCMO containing the same dispersant and 0.28 wt. %HEOS-meta borate ester (N). Corrosive wear with the two samples wascompared using the industry standard L38 Wear Test (ASTM D-5119), withthe results being provided below in Table 5. As the data of Table 5demonstrates, the addition of only 0.28 wt. % of the antiwear additiveof the invention provided an approximately 50% improvement in theantiwear results.

                  TABLE 5    ______________________________________    Additive    L38 Wear Results (mg)    ______________________________________    M           56.7    N           25.8    ______________________________________

Example 5

Lubricating oils are typically required to meet industry standards foroxidation performance. Antioxidants are normally added into these oilsto prevent the oxidative degradation that normally occurs during usage.In PCMO and ATF lubricants, phosphorous compounds, such as ZDDP orphosphites, are often used for this purpose. The following testsdemonstrate that the antioxidant effect of the HEOS meta borate esterantiwear additive of the present invention is sufficiently high to allowthe formulation of an oil without an additional ZDDP or phosphiteantioxidant.

An ATF containing Adpack N (described in Example 4) was subjected to aFord MERCON Aluminum Beaker Oxidation Test (ABOT) (Ford MERCON methodBJ110-4). The results achieved are compared to the industry standardlimits in Table 6

                  TABLE 6    ______________________________________    ABOT            Result with Adpack N                                  Industry Limit    ______________________________________    Δ total acid no. (TAN)                    1.28          <4.0    % viscosity increase @ 250 hrs.                    8.89          <40%    Diff IR @ 250 hrs.                    22.2%         <40%    % pentane insol @ 250 hrs.                    0.53          <1.0    Cu Strip @ 300 hrs.                    3b            3b max    ______________________________________

Example 6

The frictional properties of lubricating oils play a significant roletoward improving fuel economy in automobiles. Use of friction reducersallows formulators to adjust the coefficient of friction to meet theseneeds. A combination of a HEOS meta borate ester and dispersant wasfound to provide excellent friction reducing characteristics. Todemonstrate these friction reducing effects, a reference oil fullyformulated with dispersant (5.5 wt. %), antifoamant, detergent,phosphorous-based antiwear/antioxidant and demulsifier additives, butcontaining no friction reducer, was compared to the same oil furtherformulated with 2.11 wt. % HEOS meta borate ester and 7.69 wt. %dispersant (Adpack O) using a High Frequency Reciprocal Rig(HFRR) test.

In the HFRR test, a metal disc is affixed to a platen within a bath.Opposite the platen, there is provided a vibrator arm to which a mass of400 g is attached. A metal ball is affixed to the end of the vibratorarm. A sample of a lubricating oil is pipetted into the bath, immersingthe disc and the vibrator arm is lowered so that the ball contacts thedisc. The vibrator arm is then vibrated at a frequency of 20 Hz, with astroke of 1000 microns. After each five minute period the temperature ofthe oil sample is increased 20°C. (6 steps from 40° C. to 140° C.). Thedisc is then removed from the platen, and the wear scar caused bycontact with the ball is measured (diameters X and Y) using an opticalmicroscope provided with a calibrated graticule.

                  TABLE 7    ______________________________________    Temperature (°C.)                  Ref. Oil                          Ref. Oil + Adpack O    ______________________________________     40           0.12    0.099     60           0.126   0.111     80           0.133   0.115    100           0.133   0.115    120           0.134   0.116    140           0.135   0.119    ______________________________________

With the foregoing description of the invention, those skilled in theart will appreciate that modifications may be made to the inventionwithout departing from the spirit thereof. Therefore, it is not intendedthat the scope of the invention be limited to the specific embodimentsillustrated and described.

What is claimed:
 1. A sulfur-containing boroester compound selected fromthe group consisting of:alicyclic thioalkyl borate esters having thegeneral formula (I): ##STR8## wherein R₁ is a hydrocarbyl radical havingbetween about 4 to 12 carbon atoms, R₂ and R₃ are independently selectedfrom the group consisting of --(OR₄)_(n) SR₁ and --(OR₄)_(n) SR₁ OH; R₄is a hydrocarbyl radical having between about 1 to 6 carbon atoms; n isan integer of from between about 1 to 4; and l and m are independently0, 1 or 2, with the proviso that l and m are not both 0;thioalkyl-substituted cyclic meta borate esters having the generalformula (II): ##STR9## wherein n, R₁ and R₄, are defined as in formula(I); and mixtures of said alicyclic thioalkyl borate esters of formula(I) and said thioalkyl-substituted cyclic meta borate esters of formula(II).
 2. The sulfur-containing boroester compound of claim 1, whereinsaid boroester is an alicyclic thioalkyl borate ester of formula (I);said R₁ is a hydrocarbyl radical having from between about 6 to 9 carbonatoms; said R₄ is a hydrocarbyl radical having from between about 2 to 4carbon atoms; and l, m and n are all
 1. 3. The sulfur-containingboroester compound of claim 2, wherein said R₁ is a hydrocarbyl radicalhaving 6 carbon atoms; and said R₄ is a hydrocarbyl radical having 2carbon atoms.
 4. The sulfur-containing boroester compound of claim 1,wherein said boroester is a thioalkyl-substituted cyclic meta borateester of formula (II); said R₁ is a hydrocarbyl radical having frombetween about 6 to 9 carbon atoms; and said R₄ is a hydrocarbyl radicalhaving from between about 2 to 4 carbon atoms.
 5. The sulfur-containingboroester compound of claim 4, wherein each R₁ is a hydrocarbyl radicalhaving 6 carbon atoms; and each R₄ is a hydrocarbyl radical having 2carbon atoms.
 6. An oleaginous composition comprising a major amount ofan oil selected from the group consisting of lubricating oils and powertransmitting oils, and a minor amount of a sulfur-containing boroestercompound selected from the group consisting of:alicyclic thioalkylborate esters having the general formula (I): ##STR10## wherein R₁ is ahydrocarbyl radical having between about 4 to 12 carbon atoms, R₂ and R₃are independently selected from --(OR₄)_(n) SR₁ and --(OR₄)_(n) SR₁ OH;R₄ is a hydrocarbyl radical having between about 1 to 6 carbon atoms; nis an integer of from between about 1 to 4; and l and m areindependently 0, 1 or 2, with the proviso that l and m are not both 0;thioalkyl-substituted cyclic meta borate esters having the generalformula (II): ##STR11## wherein n, R₁ and R₄ are defined as in formula(I); and mixtures of said alicyclic thioalkyl borate esters of formula(I) and said thioalkyl-substituted cyclic meta borate esters of formula(II).
 7. The oleaginous composition of claim 6, wherein saidsulfur-containing boroester compound comprises from between about 0.001to 5 wt. % of said composition.
 8. The oleaginous composition of claim7, wherein said sulfur-containing boroester compound comprises frombetween about 0.02 to 1 wt. % of said composition.
 9. The oleaginouscomposition of claim 6, wherein said sulfur-containing boroestercompound is an alicyclic thioalkyl borate ester of formula (I); said R₁is a hydrocarbyl radical having from between about 6 to 9 carbon atoms;said R₄ is a hydrocarbyl radical having from between about 2 to 4 carbonatoms; and 1, m and n are
 1. 10. The oleaginous composition of claim 9,wherein said R₁ is a hydrocarbyl radical having 6 carbon atoms; and saidR₄ is a hydrocarbyl radical having 2 carbon atoms.
 11. The oleaginouscomposition of claim 6, wherein said boroester is athioalkyl-substituted cyclic meta borate ester of formula (II); said R₁is a hydrocarbyl radical having from between about 6 to 9 carbon atoms;and said R₄ is a hydrocarbyl radical having from between about 2 to 4carbon atoms.
 12. The oleaginous composition of claim 11, wherein saidR₁ is a hydrocarbyl radical having 6 carbon atoms; and said R₄ is ahydrocarbyl radical having 2 carbon atoms.
 13. The oleaginouscomposition of claim 6, wherein said oil is at least one oil selectedfrom the group of synthetic oils and natural oils.
 14. The oleaginouscomposition of claim 6, further comprising at least one additiveselected from the group consisting of: dispersants, viscosity modifiers,corrosion inhibitors, oxidation inhibitors, pour point depressants,anti-foaming agents, anti-wear agents, friction modifiers, detergentsand rust inhibitors.
 15. The oleaginous composition of claim 14, whereinsaid dispersant is a reaction product of polyisobutulene succinnicanhydride and a hydrocarbyl polyamine.